comparison Code/Descriptors/Matlab/MPEG7/calculate_HNR.m @ 4:92ca03a8fa99 tip

Update to ICASSP 2013 benchmark

+function [HNR] = calculate_HNR( y, fs, noOfFrames, silenceFrames, pitch )
+
+    %find the maximum lag M
+    DEBUG=0;
+
+    maxPeriod = ceil(fs/getVariables('getMinFreq')); %get the default minimum fundatmental frequency
+    minPeriod = floor(fs/getVariables('getMaxFreq')); %get the default maximum fundamental frequency
+
+    for i = 1:(noOfFrames - 1)
+        if( silenceFrames(i) == 1 )
+            
+            % frame is not silent
+           NA = xcorr(y(:,i), y(:,i), 'coeff');
+           NA = NA( ceil(length(NA)/2) : end );
+            
+           if(DEBUG)
+                subplot(211); plot(y(:,i)); title(i);
+                subplot(212); plot(NA); hold on;
+           end
+           
+            % find the maximum nearset to the predicted pitch
+           f0 = pitch(i);
+           if( (f0 < minPeriod) || (isnan(f0)) )
+               f0 = minPeriod;
+           end
+           % perform a search outwards from that point
+           startSearch = floor(f0-(f0*0.1));
+           endSearch = ceil(f0+(f0*0.1));
+           if( startSearch > length(NA) )
+               startSearch = length(NA) - 20;
+           end
+           if( endSearch > length(NA) )
+               endSearch = length(NA);
+           end
+           [max_value max_position] = max( NA( startSearch : endSearch ));
+           
+           if(DEBUG)
+               plot( max_position + startSearch - 1, max_value, 'gx' );
+               plot( startSearch : endSearch, NA(startSearch : endSearch), 'r');
+               hold off;
+           end
+
+           HR(i) = max_value;
+
+           if( HR(i) < 0)
+               % if the sample is negative it probably means the frame is
+               % silent so just set to  'most noisy so far'
+%                if(i>1)
+%                     HNR(i) = min( HNR );
+%                else
+                   HNR(i) = NaN;
+%                end
+           else
+                HNR(i)= 10*log10(HR(i)/(1-HR(i)));
+           end
+           if(DEBUG) title(HNR(i)); end
+        else
+            HNR(i) = NaN;
+        end
+       
+    end
+    
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